Synthesis, photophysical and nonlinear optical properties of push–pull tetrazoles. Issue 34 (10th August 2022)

• Record Type: Journal Article
• Authors: West, Anna-Kay; Kaylor, Lukas J.; Subir, Mahamud; Rayat, Sundeep
• Is Part Of: RSC advances. Volume 12:Issue 34(2022)
• Page Start: 22331
• Page End: 22341
• Publication Date: 2022-08-10
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2ra04307f
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : A 2, 5-disubstituted tetrazole with a p -nitrophenyl unit as an acceptor and a 4-( N, N -diphenylamino) phenyl group as a donor exhibits strong push–pull characteristics and displays high NLO activity. Abstract : A 2, 5-disubstituted tetrazole with p -nitrophenyl and 3-pyridyl units as acceptors (1a ), and three push–pull tetrazoles with p -nitrophenyl as an acceptor and phenyl (1b ), 2-(dibenzo[ b, d ]furan-4-yl) (1c ), and 4-( N, N -diphenylamino)phenyl (1d ) as donor groups, were synthesized by copper-catalyzed aerobic C–N coupling of p -nitrophenyl tetrazole with appropriately substituted aryl boronic acids. The absorption and emission spectra of 1a–c showed minimal dependence on the polarity of the solvent; however, in the case of 1d a blue shift was noted in the longest absorption band ( λ 1 ) as the polarity increased. The fluorescence intensity of the title compounds was found to be solvent-dependent; however, no apparent correlation to solvent polarity could be established. The absorption and emission characteristics of 1a–d were also influenced by the nature of the substituent as 1d, bearing a strong electron donating 4-( N, N -diphenylamino)phenyl group, displayed a significant red shifted absorption ( λ 1 ) as well as emission ( λ em ) bands compared to other compounds. Time dependent density functional calculations (CAM-B3LYP/6-311++G**) revealed that the longest wavelength band ( λ 1 ) is associated with an intramolecular charge transfer (ICT) from HOMO/HOMO-1/HOMO-2 → LUMO/LUMO+1 in these molecules. The first hyperpolarizability values, β HRS, of 1a–d were measured using the solution-based hyper-Rayleigh scattering technique using a femtosecond Ti:Sapphire laser and the highest NLO activity was measured for 1d with the greatest push–pull characteristics. A strong correlation was observed between the calculated hyperpolarizability ( β tot ) and experimentally measured values ( β HRS ).